Process for the preparation of aryl sulfides

ABSTRACT

Aromatic sulfides are prepared by reacting 6-20 molar proportions of certain aromatic compounds with one molar proportion of a sulfur chloride in the presence of iron at 0*50*C. The compounds have a variety of uses, including use as herbicides and fungicides.

United States Patent Fujisawa et al.

[151 3,706,805 [451 Dec. 19, 1972 [54] PROCESS FOR THE PREPARATION OFARYL SULFIDES [72] Inventors: Tamotau Fuiisawa, Yamato-shi; NoriltoOhtsuita, Sagamihara-shi; Takeo Kobori, Nalrano-ku; Genichi Tsuchihashi, Tokyo, all of Japan [73] Assignee: Sagami Chemical ResearchCenter,

Tokyo, Japan [22] Filed: Sept. 16, 1970 [21] Appl. No.: 72,821

Related U.S. Application Data {631 Continuation-impart of Sen Bio.719,743,

[52] U.S. Ci ..260/609 E, 71/98, 260/609 F, 424/337 [51] Int. Cl ..C07c149/30 [58] Field of Search ..260/609 E, 609 F, 608

[56] References Cited UNITED STATES PATENTS 2,402,685 6/1946 Signaigo..260/608 Primary Examiner-Lewis Gotts Assistant ExaminerD. R. PhillipsAttorney-Flynn & Frishauf [57] ABSTRACT Aromatic sulfides are preparedby reacting 6-20 molar proportions of certain aromatic compounds withone molar proportion of a sulfur chloride in the presence of iron at0-50C. The compounds have a variety of uses, including use as herbicidesand fungicides.

8 Claims, No Drawings PROCESS FOR THE PREPARATION OF ARYL SULFIDESRELATED APPLICATIONS This application is a continuation-in-part of Ser.No. 719,743, filed Apr. 8, 1968 now abandoned. Related application Ser.No. 720,388, filed Apr. 10, 1968 now abandoned is directed to thepreparation of polythioethers by reaction of diphenyl ether with sulfurhalides.

FIELD OF THE INVENTION The present invention relates to a process forthe preparation of aryl sulfides and to novel aryl sulfide compoundsprepared by the present process. Aryl sulfides are useful as industrialchemicals such as mothproofing agents, herbicides, lubricants,antioxidants and organic semi-conductors, as a chemical intermediate forthem, as a pharmaceutical intermediate, as a reactant in the preparationof numerous mineral oil additives, and as a starting material for thesynthesis of a multitude of sulfide derivatives. Several of such' usesare mentioned, for example, in the text: Organic Chemistry of BivalentSulfur, Volume II, E. Emmet Reid, Chemical Publishing Co., Inc., N.Y.,1960.

BACKGROUND OF THE INVENTION Various known methods for the preparation ofaryl sulfide have generally suffered from limited applicability, becausesevere reaction conditions or complicated procedures were required.Thus, a limited number of aryl sulfides have been synthesized. Forexample, only two isomers of symxylyl sulfide, i.e. bis(2,6-dimethylphenyl) sulfide and bis(2,3-dimethylphenyl) sulfide, have sofar, been reported. The method of the preparation of aryl sulfidesdisclosed by this time'may be classified into the two processes asfollows:

I. A process which involves the reaction of thiophenols or alkalisulfides with aryl halides, and

2. A process which involves the reaction of aromatic compounds withsulfur chlorides or sulfur. However, the starting materials required forprocess,( 1) are not readily obtainable, and the process requires a veryhigh reaction temperature, and process (2) usually requires a largeamount of aluminum chloride, which makes the procedure very complicatedbecause of the need of hydrolyzing the complex with aluminum chlorideinitially formed. Accordingly, neither processes can be regarded assatisfactory for use on a commercial scale.

As indicated in our parent application Ser. No. 719,743, FeCl has alsobeen found to be an effective catalyst for process (2) in which sulfurchlorides are used. However, several disadvantages weigh against the useof this catalyst. It is not as available, nor as cheap in cost as thecatalyst of this invention. It is hygroscopic and can not be usedeffectively in hydrous form in process (2), and can not be recoveredreadily following completion of reaction.

SUMMARY OF THE INVENTION This invention has as an object the preparationof aryl sulfides. A further object is the simple preparation of arylsulfides by a very economical method. A still further object is toprovide novel aryl sulfide compounds. Other objects will be apparentfrom a reading of the following description of the invention.

These objects are accomplished by reacting certain aromatic compoundswith an appropriate sulfur chloride in the presence of a trace amount ofan iron. From about 6 to about 20 molar proportions of an arcmaticcompound is used with one molar proportion of a sulfur chloride.

The present invention thus has an advantage of requiring only a traceamount of catalyst, of carrying out the reaction readily even at roomtemperature, and of simple treatment. The present invention consists ina novel sulfuration reaction which is regarded as a basic reaction ofaromatic substitution such as sulfonation, nitration, halogenation, andFriedel-Crafts reaction of aromatic compounds.

DETAILED DESCRIPTION OF THE INVENTION The catalyst employed in thepresent invention comprises an iron or an alloy thereof. Iron isgenerally used as a powder, but solid iron, even a nail promotes thissulfuration. The amount of the catalyst employed in the present processis a so-called catalytic amount, and an amount within the range of0.000] mole to 10 mole percent of catalyst per mole of sulfur chlorideis usually employed.

The sulfur chlorides which areused as the starting material in thepresent invention are sulfur monochloride (S Cl and sulfur dichloride(SCl In the system of sulfur monochloride with iron, an induction periodwas observed; however, the use of sulfur dichloride leads to a rapidformation of aryl sulfides without an induction period.

The reaction is preferably carried out in a solvent which solves thestarting materials and is inert with reactants, products and catalystsin the present reaction, but the sulfides have also been preparedwithout a solvent. Typical solvents include: diethylether, carbontetrachloride, chloroform and dichloromethane. Carbon tetrachloride ispreferred.

The molar ratio of aromatic compound to sulfur chlorides employed in theprocess of this invention is from about 6 to about 20, preferably fromabout 9 to about 12. The upper limit of the amount of aromatic compoundpresent in the reaction mixture appears to be governed only by economicconsiderations. However, as a practical matter, the molar ratio ofaromatic compound to sulfur chlorides generally will not exceed about20.

The sulfuration goes forward at temperature over a wide range, such as 0to C., butinitiates most readily when kept standing at room temperature.A preferred temperature is from 0 to 50C. Under these conditions thereaction is, in general, exothermic and goes forward to completion withgood yield calculated upon the basis of consumed starting materials.

This reaction is most advantageously carried out in the absence oflight, for avoiding the formation of byproducts from thedisproportionation of the sulfur chlorides.

In practicing this invention usually an excess of aromatic compound isallowed to react at room temperature with 0.03 to 0.05 percent by weightof the catalyst while an appropriate sulfur chloride is added. Theevolution of hydrogen chloride commences soon after the addition ofsulfur chloride is started, and the reaction is complete when no morehydrogen chloride is evolved. The aryl sulfide product is isolated by atreat- Example 1 To a solution of 215 parts of anisole in 720 parts of 7dry diethyl ether was added 135. parts of sulfur monochloride. When atrace amount (0.10 0.30 parts) of iron powder was added to this ethersolution, an exothermic reaction began to-take place with an evolutionof hydrogen chloride gas after an induction period ofa few minutes. Thereaction mixture was stirred for one hour at room temperature tocomplete the reaction. Distillation under reduced pressure gavebis(4-methoxyphenyl) monosulfide which boiled at 140 l55C/0.2 mmHg.Recrystallization from ethanol afforded 88 parts (37 percent yield) of asample which melted at 45- 46C.

The results obtained by the use of iron catalyst in the reaction ofanisoleand sulfur monochloride are given in Table 1.

TABLE 1 Catalyst Induction Yield of (0.1 0. 3 parts) period of thebis(4-methoxyphenol) reaction monosulfide Fe 3 -4 min. 37

The yields of bis(4-methoxyphenyl) monosulfide by the reaction ofanisole with sulfur monochloride in the absence of any solvent catalyzedby iron with various molar ratios of the reactants are shown in Table 2below. 7

Table 2 Molar ratio S,Cl,

Yield Example 2 for one hour at room temperature to complete thereaction. Distillation under reduced pressure gave bis-(4-methoxyphenyl) monosulfide with a boiling point of 140 lS5C./0.2mmHg, which was recrystallized from ethanol to give 88 parts (37 percentyield) of a sample with a melting point of 45 46C.

Example 3 A red glass flask, which is shielded from light of wave lengthbelow 6000 A, fitted with a magnetic stirrer bar, a red-glass droppingfunnel and a condenser was flushed with nitrogen. In the flask wereplaced 1.0 mole of anisole and ca. 30 mg of iron-powder at roomtemperature. Then a solution of 0.1 mole of an appropriate sulfurchloride in 20 ml of carbon tetrachloride was added in portions over aperiod of 2 hours. The mixture was stirred until the evolution ofhydrogen chloride was complete (ca. 1 hour). Bis(4-methoxy-phenyl)monosulfide was isolated by distillation followed by recrystallizationfrom ethanol. Yield; Fe-S Cl, system 74%, and Fe-SCl, system I Example 4(Comparative Example) The procedure of Example 3 was'repeated exceptthat the reaction carried out in the presence of light. Yield; Fe-S Clsystem 69%, and Fe-SCl, system 57%.

Example 5 The procedure of Example 3 was followed, however, thereactants, and catalyst were:

phenetole 1424 parts S Cl 135 parts iron powder 0.3 0.5 part(phenetolels Cl 1 1.7). The yield of bis(4-ethoxyphenyl) monosulfide was78 percent. This sulfide is in the form of white needles and has amelting point of 55- 56C.

Example 6 The procedure of Example 3 was followed, however, thereactants and catalyst were:

phenetole 1420 parts SCI, 103 parts iron powder 0.3 0.5 part(phentole/SCl, 1 1.6). The yield of bis(4-ethoxyphenyl) monosulfide was74 percent.

Example 7 Again the procedure of Example 3 was employed. The reactantsand catalyst were:

diphenyl ether 680-parts 82C]: pans iron powder 0.3 0.5 part (diphenylether/S=Cl, 8).

The product obtained was bis(4-phenoxyphenyl) monosulfide in the form ofleaflets. The sulfide has a melting point of 101 102C.The yield waspercent.

Elemental Analysis. Found: C, 77.39; H, 4.98

Calculated for C, H 0,S: C, 77.84; H, 4.86.

This substance has not been reported so far in the literature, and itsstructure was identified as a parasubstituted sulfide by examination ofits infrared absorption spectrum (1900Cm" and 840 cm").

The procedure of Example 3 was employed with the following reactants andcatalyst:

m-xylene 85 grams S Cl 13.5 grams iron powder 30 mg (m-xylene/S Cl 8).

The product obtained was a' mixture of tetramethyldiphenyl monosulfides,having a boiling point of 137 14 lC./mmHg. Yield was 71 percent.

This product separated by distillation into bis(2,4- dimethylphenyl)monosulfide having a boiling point of 125 l27C./0.36 mmHg (yield 93percent), and 2,4- dimethylphenyl 2,6-dimethylphenyl monosulfide havinga melting point of 53 54C. (yield 7 percent). Both of these compoundsare novel compounds.

Example 9 The procedure of Example 3 was employed with the followingreactants and catalyst:

m-xylene 850 parts SC1 105 parts iron powder 0.3 0.5 part (m-xylene/SCl-8). A mixture of tetramethyldiphenyl monosulfides was obtained. Themixture has a boiling point of 122 l26C./mmHg. The yield was 63 percent.The

mixture was fractionated, by distillation into bis(2,4-

dimethylphenyl) monosulfide (yield 89 percent) and-2,4-dimethylphenyl-2,6-dimethylphenyl) monosulfide (yield 1 1 percent).

As indicated above, the sulfides have activity as herbicides andfungicides. The herbicidal activity of bis(4- methoxyphenyl) monosulfide(Example 3, above) was evaluated. The compound is applied to a soil inwhich the seeds of Cyperus japonica, Millet grass and Stellarica AlsiueVar. undulata, and rice plant seeds are contained. Cyperus japonica is agrass known as one of the most resistant to herbicides.

Firstly, 50 g of the soil was charged into a pot made of polystyrene,having a surface area of about l/200 m and then the seeds were seededinto the surface of the soil. Thereafter, about 10 cc of an aqueoussolution containing 1,000 ppm of the test compound was added to thesurface of the soil at a dosage of 200 g per acre (100 mg/pot). Further,the treated soil was maintained in status of a paddy field by theaddition of water, and was allowed to stand in a greenhouse at aconstant temperature of 25C. 14 days after the treatment, the soiltreating activity was examined. Through this procedure, the followingresults were obtained.

SOIL TREATING ACTIVITY Stellarica ALriue Var. undulata Cyperus Milletjaporu'ca gras -+l-+ Activity is very large Activity is medium Activityis small No activity.

The fungicidal activity of bis(4-methoxyphenyl) monosulfide (Example 3)was also evaluated with respect to Pelliculan'a sasakii (P.S.) andPyricularia aryzae (P.O.). The test compound containing an aqueoussolution in the following on nce plants grown to 3 or 4 foliarstage 1n agreenresults are obtained.

Test Concentration P.S. P.O. Compound Bis(4-methoxy- 500 ppm *46 *sophenyl) sulfide These values are calculated from the following formula:

The percentdisease control =(A- B)/A X A: The number of lesional spotsper foilage in an untreated plant. B: The number of lesional spots perfollage in a treated plant.

As seen from the foregoing test results, the compound,bis(4-methoxyphenyl) monosulfide, is useful as a fungicide which doesnot contain chlorine or arsenic.

What we claim is:

1. Process for the production of an aromatic monosulfide whichcomprises:

reacting from about 6 to about 20 molar proportions of an aromaticcompound selected from the group consisting of anisole, phenetolediphenyl ether, xylene and diphenyl sulfide, with one molar proportionof a sulfur chloride in the presence of a catalytic amount of a catalystconsisting essentially of metallic iron at a temperature of from 0 to50C. in the presence of a non-aqueous solvent and recovering saidaromatic monosulfide from the resulting reaction mixture.

2. Process of claim I, wherein from about 9 to about 12 molarproportions of the aromatic compound are employed.

3. Process of claim 1, wherein the non-aqueous solvent is selected fromthe group consisting of diethylether, carbon tetrachloride, chloroformand dichloromethane.

4..Process of claim 1, wherein the non-aqueous solvent is carbontetrachloride.

5. Process of claim 1, wherein reaction is conducted in the substantialabsence of light.

6. Process of claim 1, wherein the catalyst is employed in the range of0.0001 10 mole percent per sulfur chloride.

7. Process of claim 1, wherein the chloride is sulfur monochloride.

8. Process of claim 1, wherein the chloride is sulfur dichloride.

concentration is sprayed

2. Process of claim 1, wherein from about 9 to about 12 molarproportions of the aromatic compound are employed.
 3. Process of claim1, wherein the non-aqueous solvent is selected from the group consistingof diethylether, carbon tetrachloride, chloroform and dichloromethane.4. Process of claim 1, wherein the non-aqueous solvent is carbontetrachloride.
 5. Process of claim 1, wherein reaction is conducted inthe substantial absence of light.
 6. Process of claim 1, wherein thecatalyst is employed in the range of 0.0001 - 10 mole percent per sulfurchloride.
 7. Process of claim 1, wherein the chloride is sulfurmonochloride.
 8. Process of claim 1, wherein the chloride is sulfurdichloride.